Here is the full list of all 20 Ghost of a Tale achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Complete the game without alerting any guards.
Complete the game without getting hit by an enemy.
Reach the end of the game.
Complete the game without ever eating to regain energy.
Learn all skills in the adventure.
Finish every secondary quest.
Set fire to all inflammable items in Dwindling Heights.
Complete the full set of Duinlan's armour.
Rid Dwindling Heights of all spiders.
Unlock forty-five footnotes.
Play all songs during the course of the game.
Discover the name of every possible character in Dwindling Heights.
Steal all of the Rat Guards' handkerchiefs.
Reach the desolate shore.
Complete all of Gusto and Fatale's quests.
Discover Duinlan’s tomb.
Open all window shutters.
Gather fifty-five mushrooms.
Reach the highest point in the highest tower.
Escape from Tilo’s cell.